In this file photo, Saudi Interior Minister Prince Nayef is seen during an interview with The Associated Press at his office in Riyadh, Saudi Arabia. (Feb. 5, 2012) Photo Credit: AP

RIYADH, Saudi Arabia - The death of Saudi Arabia's Crown Prince Nayef bin Abdul-Aziz on Saturday means that — for the second time in less than a year — the key Western ally must pick an heir to the 88-year-old King Abdullah, who has already outlived two designated successors. Nayef, who was named the king-in-waiting in November, had been out of the country since late May, when he went on a trip described as a "personal vacation" that would include medical tests. He travelled abroad frequently in recent years for tests, but authorities have never given details on any ailments.

Prince Nayef was the interior minister who spearheaded Saudi Arabia's fierce crackdown that crushed al-Qaida's branch in the country after the 9/11 attacks. He was in his late 70s. He had a reputation for being a hard-liner and was seen as close to the powerful Wahhabi religious establishment that gives legitimacy to the royal family. His elevation to crown prince after the death of his brother, Prince Sultan, had raised worries among liberals that he could roll back the modest reforms of King Abdullah if he reached the throne.

Nayef had expressed some reservations about some of the reforms by Abdullah, who made incremental steps to bring more democracy to the country through municipal elections and increase women's rights. Nayef said he saw no need for elections in the kingdom or for women to sit on the Shura Council, an unelected advisory body to the king that is the closest thing to a parliament.

In 2009, Nayef promptly shut down a film festival in the Red Sea port city of Jiddah, apparently because of conservatives' worry about the possibility of gender mixing in theaters and a general distaste toward film as immoral.

The anti-militant campaign also boosted Nayef's ties to the religious establishment, which he saw as a major tool in keeping stability and preventing the spread of violent al-Qaida-style "jihadi" theology. The Wahhabi ideology that is the official law in Saudi Arabia is deeply conservative — including strict segregation of the sexes, capital punishments like beheadings and enforced prayer times — but it also advocates against al-Qaida's calls for holy war against leaders seen as infidels.

His top concern was security in the kingdom and maintaining a fierce bulwark against Shiite powerhouse Iran, according to U.S. Embassy assessments of Nayef.

"A firm authoritarian at heart," was the description of Nayef in a 2009 embassy report on him, leaked by the whistleblower site WikiLeaks.

"He harbors anti-Shia biases and his worldview is colored by deep suspicion of Iran," it said. "Nayef promotes a vision for Saudi society under the slogan of 'intellectual security,'which he advocates as needed to 'purge aberrant ideas'" and combat extremism, it added, noting that his was in contrast to Abdullah's strategy emphasizing "dialogue, tolerance of differences, and knowledge-based education that is objectionable to many conservatives."

WHO IS THE LIKELY SUCCESSOR AS CROWN PRINCE?

Nayef's brother, the 76-year-old Prince Salman, is widely expected to be selected as crown prince by Saudi Arabia's Allegiance Council, an assembly of sons and grandsons of the country's first monarch, the late King Abdul-Aziz.

Salman is the current defense minister and, like Nayef, a son of the country's founding monarch. For more than four decades, Salman was governor of Riyadh, the country's capital.

Analysts believe he shares many of Nayef's conservative views and is unlikely to challenge the religious establishment if made king. But he also has played more of a mediator role in Saudi politics while in charge of the Riyadh region.

"There has been an impression that Nayef is more conservative because he was the guy dealing with threats and terrorism as interior minister and Salman was meeting with businessman and intellectuals as governor of Riyadh," said Sami al-Faraj, director of the Kuwait Center for Strategic Studies.

"The reality is there is very little difference. Both are conservative and won't rock the boat," he added. "Nayef was just a behind-the-scenes guy and Salman is more public. One was implicit; the other explicit."

WHAT DOES IT MEAN FOR THE FUTURE?

Until now the successor has been chosen from the sons of King Abdul-Aziz but the deaths of two crown princes mean the Saudi leadership can turn to a younger generation, his grandsons, and put them in positions to groom them as potential rulers. This would mark an important shift in Saudi affairs by acknowledging that the country is moving toward a new era under the stewardship of a generation raised with deeper Western connections and understandings.

It's still unclear, however, whether Nayef's death will bring about the shift to put a younger member of the royal family in a traditional role as No. 3 in line for the throne. Among the possible contenders mentioned include King Abdullah's son Mitab, the head of the National Guard, and Nayef's son Mohammad, a senior official in the interior ministry.

WHAT ARE THE ISSUES AHEAD FOR SAUDI ARABIA?

Saudi Arabia is the main Arab rival to Iran and is deeply worried about Tehran's nuclear program. Iran insists it does not seek nuclear weapons, but Saudi officials and their Western allies fear the country could develop a nuclear arsenal and significantly shift the balance of power in the region. One possible outcome could be a regional nuclear arms race with Saudi Arabia also seeking atomic weapons.

Saudi Arabia is also facing Arab Spring-inspired internal pressures for political reforms and greater openness. King Abdullah has pledged billions of dollars to create more state jobs and offer other government-backed programs to try to appease calls for change.

Neighboring Bahrain, meanwhile, has become a central issue for Saudi Arabia since a Shiite-led uprising last year against the ruling Sunni monarchy. Saudi forces led a Gulf military intervention to help prop up the dynasty in the strategic island nation, which is home to the U.S. Navy's Fifth Fleet. Saudi Arabia is now leading efforts for closer union with the country that would effectively unify key policies such as security and foreign relations. More than 50 people have died in Bahrain's unrest since February 2011.